Most definitely. What's considered "over the line" changes with societal values. Racist and sexist jokes are widely considered to be in poor taste currently, but it was not always so. For the most part, comedians can get away with making light of an ethnic group or sexual identity that they belong to themselves. Personally, I think the most successful comedians are the ones who can get us to laugh at ourselves instead of laughing at some perceived "other."

Does "over the line" mean the same thing as "going too far?" Because one could definitely take a joke too far and then ruin it aesthetically, while in another way how (un)funny a joke is will be determined subjectively. Still, there is a difference between rudeness and crudeness, content and delivery.